Flame resistant composition containing polymeric phosphorylated amides

ABSTRACT

Highly fire resistant composites or laminates particularly applicable as structural components in aircraft, e.g. in the engine nacelle, as part of the acoustic panel-fire wall structure, and capable of withstanding a 2,000° F. flame temperature, comprising incorporating an additive in the form of a polymeric phosphorylated amide, into a resin, e.g., a polyimide or an epoxy resin, such additive being soluble in the resin. The resulting resin containing the additive is then applied to or impregnated into a substrate such as glass fiber cloth or graphite fiber, to form a composite structure which is then cured. The resulting cured composite when subjected to high temperatures of the order of, e.g., a 2,000° F. flame temperature, forms a resin char of reduced thermal conductivity which holds the fibers of the laminate together and maintains the structural stability and integrity of the laminate.

BACKGROUND OF THE INVENTION

This invention relates to thermal insulation materials having high fireresistance and low thermal conductivity, and is particularly concernedwith resin compositions and composites, particularly polyimide or epoxyresin compositions, and composites formed therewith, incorporatingcertain additives to substantially increase fire resistance, and whichare particularly applicable as structural components, e.g., as anacoustic panel-fire wall structure in aircraft.

Considerable effort and funds have been expended over the past severalyears in programs to develop the potential of organic compositematerials for use in aircraft structures, among others. These studieshave shown that the use of high-stiffness, high-strength composites,such as graphite-epoxy, can reduce the weight of structural componentsby as much as 50%, and thus improve structural efficiency whileproviding significant benefits in cost and performance. The mostcommonly employed class of resins for this use, depending upon theparticular application, are epoxides, polyesters, phenolics andpolyimides.

Thus, using graphite-polyimide as the composite, a structural componentis available that has good strength, is lightweight, and has some fireresistance, in that the polyimide will not readily burn at lowtemperatures. However, at 2,000° F. flame conditions, the polyimide willburn and decompose to form a char on the flame side. This char, though,is so thin that it will allow heat to get through to the backside anddecompose the resin. Thus, this could create a hazard due to thepossibility of the decomposition products igniting, thereby generating afire on the backside, even though the parent polymer e.g. polyimide,does not readily burn. Furthermore, with the resin volatilizing, orburning away, the heat transfer through the backside is sufficient toignite other combustible articles in contact with this fire wall.Therefore, a need exists for a non-burning resin composite that has goodstability, is a good char former, and has low thermal conductivity.

There are two problem areas where such a non-burning resin compositioncan be used on an aircraft: (1) in the engine nacelle, as part of theacoustic panel-fire wall structure, and for this application, polyimidesare particularly desirable; and (2) as part of the external surfacewhere graphite-epoxies are the usual materials of construction.

In regard to this latter case, instances have been reported of theresultant degradation of graphite-epoxy composites due to fire and theconsequent breaking up of the graphite fibers and the spreading of thesefibers to electrical equipment. Thus, any method that is developed tocontain these short conductive fibers and prevent their spreading wouldbe of great value.

Therefore, the use of graphite fiber-resin composites depends not onlyon the strength of the composite due to the presence of the graphite,but on the fire resistance of the resin, as well. There are manyadditives that, when incorporated into the resin, will act as fireretardants. Some, such as alumina trihydrate, ammonium phosphate, andzinc borate, are solids that offer excellent fire resistance. Thehydrated alumina will offer fire protection by giving off water at arelatively low temperature; however, this temperature is usually aroundthe processing temperature of some resins, e.g., polyimides. Ammoniumphosphate and zinc borate are effective at higher temperatures, but, aswith the hydrated alumina, these are all solid particulates, and theyadversely affect the mechanical properties of the laminate, i.e. causeincrease in laminate thickness with a consequent decrease in strength.Many other additives are available that are soluble in the resin, butthey are good fire retardants only at relatively low fire temperatures,i.e. around 500° F. to 1,000° F.

There accordingly has arisen the need for a substance which can beincorporated into the resin and which will give protection to the resinat high temperatures, e.g., of the order of 2,000° F., to provide aresin composition which is non-burning and has a low thermalconductivity, and wherein such substance functions as a char stabilizer.However, use of resin-soluble additives for this purpose such as thereaction product of hydroquinone and phenylphosphonic dichloride,although alleged to be a fire retardant when impregnated into clothing(Ger. Offen. Nos. 2,236,038, Jan. 31, 1974; 2,236,039, Jan. 31, 1974;2,346,787, Apr. 3, 1975; U.S. Pat. Nos. 3,853,819, 3,894,986; 3,900,444;and 3,941,752), will not withstand temperatures much above 1,000° F.Thus, for aircraft utilization, whether in the engine nacelle, or on theexternal skin, where burning fuel fires could result in temperaturesaround 2,000° F., any organic-soluble additive that can result in astabilized char upon burning is needed.

It has been known that phosphorus derivatives make good fire retardingagents, as exemplified by the following: U.S. Pat. Nos. 3,941,752;3,900,444; 3,894,986; 3,853,819; 2,577,281; 2,642,413; 2,716,639;3,450,677; 3,640,823; 3,685,974; and 3,712,789. U.S. Pat. No. 2,642,413uses an organo-phosphonic acid diamide and forms polymers thereof withureas. U.S. Pat. No. 3,450,677 prepares polymers from a diamine and anorganic phosphite, phosphonite or phosphonic dihalide. The resultingmaterials are then treated with isocyanates to prepare polyureas, butare not employed as additives for resin composites.

However, much of the work with fire retardant compositions has beenconcerned with incorporation of various phosphorylated derivatives intopolyurethanes, or fiber forming compositions. Furthermore, in mostcases, these compositions have had to be stable to relatively low flameconditions, such as burning wood, e.g., up to about 800°-1,000° F. Whenincorporated into a glass cloth polyimide resin laminate and burned at2,000° F. (the FAA requirement for burn-through stability), they did notpass.

However, certain compounds have been used as fire retardants that werefound to show excellent fire resistance to a 2,000° F. flame. Notableamong these was ammonium phosphate.

Accordingly, one object of the invention is to provide resincompositions and composites having high fire resistance and low thermalconductivity. Another object is the provision of compositions andcomposites of the above type having utility as a fire barrier,particularly applicable as an aircraft structural component, e.g., anacoustic panel-firewall structure capable of withstanding hightemperature, e.g., a 2,000° F. flame temperature. A still further objectis the provision of resin compositions, particularly polyimide and epoxycompositions, and composites produced therefrom, such as polyimide-glassfabric or epoxy-glass fabric composites or laminates, havingincorporated therein a substance which substantially increases the fireresistance of the resin and reduces its thermal conductivity,substantially without adversely affecting the physical and mechanicalproperties of the composite, and which functions to stabilize the resinor resin char, at high temperatures, e.g., a 2,000° F. flametemperature, and maintains the structural integrity of the composite.

SUMMARY OF THE INVENTION

The above objects and advantages are achieved, according to theinvention, by incorporating into a resin such as a polyimide or anepoxy, a polymeric phosphorylated amide, particularly in the form of anamide of various organic phosphonic and thiophosphonic acids or theiresters with various diamines, as described in greater detail below. Suchcomposition is then applied to a suitable substrate, such as glasscloth, to form a "prepreg," and the resin, such as polyimide or epoxy,is cured to obtain a fire resistant composite or laminate.

The additive incorporated into the resin, as noted above, can be, forexample polymers of organic phosphonic and thiophosphonic acid amides,and which can be substituted by aliphatic or aromatic groups. Suchcompounds are soluble in the above noted resins, e.g. polyimide orepoxy, and upon curing of the resin composition and composite containingsuch compounds or additives, there is no adverse effect on themechanical properties of the cured composite or laminate. Such compositeoffers substantial protection against burning, particularly at hightemperatures, e.g., at 2,000° F. and above. At such temperatures, e.g. a2,000° F. flame condition, the presence of a sufficient amount of theabove additive in the composite results in stabilization of the resinchar which is formed. This enables such char to hold the fibers of thesubstrate, e.g. glass or graphite fibers, together and maintain thestructural stability and integrity of the composite or laminate. Theresin char also has reduced thermal conductivity due to the heatdissipation capability of the carbonaceous residue.

The polymeric phosphorylated amide according to the invention,preferably is incorporated into a polyimide or epoxy resin. Suchpolyimide can be either a condensation type polyimide or an additiontype polyimide. Epoxy resins which can be employed include the epoxyresin produced by condensation of bisphenol A and epichlorohydrin. Otherresins into which the polymeric phosphorylated amide additive of theinvention also can be incorporated include polybenzimidazoles,polyesters, polyquinoxylines, polyacrylates, phenolic polymers andsilicones, in order to enhance their fire resistance. Thepolybenzimidazole is the reaction product of 2,2'-diamino benzidine withthe phenyl ester of p,p'-diphenyl ether benzoic acid; thepolyquinoxyline is the reaction product of 2,2'-diamino benzidine with abisbenzene glyoxal. Examples of phenolic polymers which can be employedare the phenol-formaldehyde resins, and examples of silicones aredimethyl polysiloxanes and methyl phenyl polysiloxanes. Examples ofpolyacrylates are polymethyl acrylate and polymethyl methacrylate. Ithas been found that the polymeric phosphorylated amide additives arecapable of chemically bonding to the above resins and become an integralpart of the cured resin composition, and not merely an admixture of theadditive and the resin. Thus, the additive cannot be leached out of thecured composition.

The polymeric phosphorylated amide additive such as, for example,polyphenyl phosphonic polyamide, can be added to the resin, e.g.polyimide, in varying proportions, e.g. ranging from about 5 to about 40parts, preferably about 10 to about 40 parts, per 100 parts of resin,e.g. polyimide, by weight, to produce the resin compositions of theinvention.

Substrates to which the resin compositions of the invention can beapplied, include graphite fibers or fabric, glass fibers or fabric,particularly high silica glass fabric such as the material marketed as"Refrasil", low melting point metals such as aluminum, and the like. Theresin composition containing the polymeric phosphorylated amideadditives, e.g. polyimide containing a poly phenyl phosphonic polyamide,and substrate, can be formed into several plies to produce a compositeor laminate, and cured.

In addition to use in aircraft engines, the composites of the inventioncontaining the above additive can also be used as fire walls in homes,in autos (between the passenger compartment and either the engine or thegas tank), in trains, etc.

DESCRIPTION OF PREFERRED EMBODIMENTS

As previously noted, the additive employed according to the invention,i.e. the polymeric phosphorylated amide, can be employed in an amountranging from about 5 to about 40 parts, per 100 parts of resin or resinsolids, by weight, but preferably is employed in an amount ranging fromabout 10 to about 40 parts, per 100 parts of resin or resin solids, byweight. The additive employed can be either a homopolymer or acopolymer. For the homopolymer, the general formula is: ##STR1## where Yis O or S; R is H, alkyl, with straight chain or branched chain, andgenerally containing from about 1 to about 6 carbon atoms, e.g., methyl,ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, and isohexyl;cycloalkyl, generally containing from about 5 to about 7 carbon atoms,such as, for example, cyclopentyl, cyclohexyl, methylcyclohexyl; aryl,generally containing from about 6 to about 14 carbon atoms, such asphenyl, xylyl, tolyl, naphthyl, methylnaphthyl and ethylnaphthyl; thecorresponding halogenated alkyl and aryl groups including, for example,the chlorinated, brominated and fluorinated derivatives, e.g.trichloromethyl and chlorophenyl, nitroaryl containing about 6 to about14 carbon atoms such as nitrophenyl, nitrotolyl, and the like;heterocyclic containing 5 to 6 members in the heterocyclic nucleus, andO, N or S as hetero atoms, e.g., furanyl, pyridyl, pyrrolyl, quinolyland thiophene; amino, alkylamino containing from about 1 to about 8carbon atoms in the alkyl group, e.g., methylamino, ethylamino,dimethylamino, diethylamino, arylamino containing from about 6 to about14 carbon atoms such as phenylamino and naphthylamino, oxyalkylcontaining from 1 to about 4 carbon atoms such as oxymethyl, oxyethyl,oxypropyl, and oxyaryl containing about 6 to about 14 carbon atoms suchas oxyphenyl, oxytolyl and oxynaphthyl, and the like; X is --NR₁--R₂)_(c) NR₁ --, where R₁ is H, alkyl, cycloalkyl, aryl, all asdescribed above, acyl containing about 1 to about 7 carbon atoms such asformyl, acetyl, propionyl, and including cycloalkylacyl such ascyclohexylacyl, aroyl containing about 7 to about 11 carbon atoms suchas benzoyl, naphthoyl and the like; and R₂ is alkylene of from about 2to about 14 atoms, such as ethylene, propylene, and the like, arylene offrom about 6 to about 14 carbon atoms, such as divalent phenylene,biphenylene, naphthylene and anthracene; divalent carbonyl andthiocarbonyl, >C═NH, cycloalkylene of from about 6 to about 8 carbonatoms, such as cyclohexylene; and where c is 0 to 2; n is 1 to about1,000, usually 1 to about 100; and A is the terminal group --NR₁ R₃where R₃ has the same values as R₁, and R₁ and R₃ can be the same ordifferent.

For the copolymers the general formula is: ##STR2## where A and Y arethe same as for the homopolymer; R₄ can have any of the values describedabove for R, and R and R₄ can be the same or different, and X' and X"can have any of the values described above for X, and X' and X" can bethe same or different, and where the relationship between R and R₄, andX' and X" is such that when R and R₄ are different, X' and X" are thesame, and when R and R₄ are the same, X' and X" are different; s and tcan be the same or different and where s and t are from about 1 to about10, and n has the same values noted above for the homopolymer.

Preferred additives are those wherein R is hydrogen, alkyl, aryl or thechlorinated derivatives thereof.

Another preferred class of polymers according to the invention are thepoly phosphinohydrazides, poly phosphinoguanides and their thio analogs.Such polymers have the following recurring structural units: ##STR3##where Y and R have the values defined above.

Examples of specific polymeric additives and their recurring structuralunits, according to the invention are:

                                      TABLE                                       __________________________________________________________________________    POLYMERIC PHOSPORYLATED AMIDES                                                __________________________________________________________________________    (1)                                                                                ##STR4##                              Poly (Phenyl Phosphonic                                                       Polyamide)                         (2)                                                                                ##STR5##                              Poly (p-Phenylenediamine                                                      Phenyl Phosphonic Acid Amide)      (3)                                                                                ##STR6##                              Poly (m-Phenylene Diamine                                                     Phenyl Phosphonic Acid Amide)      (4)                                                                                ##STR7##                              Poly (1,8-Naphthalene Diamine                                                 Phenyl Phosphonic Amide)           (5)                                                                                ##STR8##                              Poly (p-Phenylene Diamine                                                     Phenylthiophosphonic Amide)        (6)                                                                                ##STR9##                              Poly (p-Phenylene Diamine                                                     Amido Methyl Phosphonate)          (7)                                                                                ##STR10##                             Poly (Urea Phosphinate)            (8)                                                                                ##STR11##                             Poly (Biuret Phosphinate)          (9)                                                                                ##STR12##                             Poly (Urea Methyl                                                             Phosphonate)                       (10)                                                                               ##STR13##                             Poly (Biuret Methyl                                                           Phosphonate)                       (11)                                                                               ##STR14##                             Poly (Urea Trichloromethyl                                                    Phosphonate)                       (12)                                                                               ##STR15##                             Poly (Biuret Trichloromethyl                                                  Phosphonate)                       (13)                                                                               ##STR16##                             Poly (Ethylenediamine                                                         Phosphinate)                       (14)                                                                               ##STR17##                             Poly (Ethylenediamine Methyl                                                  Phosphonate)                       (15)                                                                               ##STR18##                             Poly (Ethylenediamine                                                         Trichloro- methyl                                                             Phosphonate)                       (16)                                                                               ##STR19##                             Poly (Guanidine Methyl                                                        Phosphonate)                       (17)                                                                               ##STR20##                             Poly (Phosphorylated                                                          Melamine)                          (18)                                                                               ##STR21##                             Poly (Hydrazyl Phosphinate)        (19)                                                                               ##STR22##                             Poly (Hydrazyl Methyl                                                         Phosphonate)                       (20)                                                                               ##STR23##                             Poly (Hydrazyl Trichloromethyl                                                hosphonate)                        (21)                                                                               ##STR24##                             Poly (2,6-Diaminopyridyl                                                      Trichloromethyl Phosphonate)       (22)                                                                               ##STR25##                             Poly (co-Hydrazyl Methyl                                                      Phosphonate Phosphinate)           (23)                                                                               ##STR26##                             Poly (co-Ethylenediamine                                                      Hydrazyl Trichloromethyl                                                      Phosphonate)                       (24)                                                                               ##STR27##                             Copolymer from Dimethyl Methyl                                                hosphonate plus                                                               Ethylenediamine and Hydrazine                                                 (Hydrate)                          __________________________________________________________________________

The compounds of the invention above can be prepared in various ways, asillustrated in the examples below.

EXAMPLE I

The 1:1 molar reaction of phosphonic dichlorides with diamines is givenin the representative reaction of phenylphosphonic dichloride withpara-phenylene diamine, below. Two methods were used. One involved useof triethylamine as the acid acceptor and the other a high boilingsolvent, such as bromobenzene, to decompose the amine hydrochlorideformed. In the first case, one mole of para-phenylenediamine and twomoles of triethylamine were mixed in one liter of methylene chloride.One mole of phenylphosphonic dichloride was then added dropwise. Anexothermic reaction occurred, and after the addition was complete, themixture was heated to reflux for two hours. The solvent was evaporatedand the resultant solid slurried in about two liters of warm water toremove the triethylamine hydrochloride. The polymer was filtered undervacuum and the dried polymer had a softening point around 240° C.

The second method used the same ratios of reactants, but bromobenzenewas used as a solvent, with no triethylamine. In this system, themixture was heated to reflux for about 40 hours to remove the HCl. Thisproduct had a softening point around 225° C.

EXAMPLE II

Other substituted diamides were also prepared, and representative ofthis type of reaction are the reactions of phosphonic acid esters withvarious diamines, e.g. urea, guanidine, hydrazine and ethylene diamine,among others. Thus, one mole of dimethyl methylphosphonate [CH₃ P(O)(OCH₃)₂ ] and one mole of urea were mixed in 130 mls of xylene. Thereaction was heated to 130° C. for 48 hours and the xylene decanted offto leave behind an extremely viscous polymer. Another similar reactionwas that between 0.5 moles of the dimethyl methylphosphonate and 0.5moles of ethylene diamine in 250 mls of methylene chloride. After allthe diamine had been added dropwise, the reaction mixture was allowed tostand 72 hours at room temperature. The methylene chloride wasevaporated off and the reaction mixture heated first to 65° C. for 4hours, then 120° C. for 4 hours. A viscous polymer resulted.

EXAMPLE II-a

Dimethylphosphite, in the amount of 336.5 g (3.04 moles), was dissolvedin 1 liter of xylene in a 2-liter resin kettle fitted with a stirrer,Claisen takeoff head, and a condenser. The mixture was cooled with a dryice-ethylene glycol bath and 155 g (3.1 moles) of hydrazine hydrate wereadded slowly. The mixture was allowed to warm to room temperature andleft to stir overnight. It was then heated to reflux (60° C.) for 48hours, at which time alcohol and water were distilled off until thetemperature rose to 140° C. It was refluxed at this temperature for twohours and then about 600 mls of xylene were distilled off. The remainingsolution was transferred to a beaker, cooled, and the excess xylene wasdecanted off. The beaker was heated in a vacuum oven to remove the lasttrace of xylene to yield a viscous, slightly yellow poly(phosphinohydrazide), where Y is O and R is H in formula (c) above.

EXAMPLE II-b

Dimethyl methylphosphonate, in the amount of 620.4 g (5 moles), wasplaced in a 2-liter resin kettle, equipped as above. It was cooled in adry ice-ethylene glycol bath and 251 g (5 moles) hydrazine hydrate wereslowly added. The mixture was left to stir overnight and then heated todistill off the alcohol and water. The residue was a very viscous, lightyellow product, poly(methylphosphinohydrazide), where Y is O and R isCH₃ in formula (c) above.

The phosphorylated amide additives can be added to the resin, e.g.polyimide, in the required amount, and the resulting mixture applied tothe substrate such as graphite fabric or glass fabric, to form acomposite or laminate utilizing, e.g. a plurality of fiberglass orgraphite cloth plies. The composite is heated at elevated temperatureranging from about 200° to about 350° F. for curing, usually, althoughnot necessarily, followed by a post curing operation at highertemperatures, e.g. ranging from about 400° to about 600° F.

The polymeric phosphorylated amide additive is added to the resin, e.g.polyimide, or such additive can be first incorporated in a solvent suchas N-methyl pyrrolidone, and the resulting solution is then employed toimpregnate the substrate such as graphite fabric or glass cloth, to forma composite or laminate, which is then cured as noted above.

The cured composites or laminates are subjected to flame tests employinga burner flame at a temperature of 2,000° F. In these tests the samplecomposite is mounted vertically, and the flame is impinged on the frontface of the composite or laminate, and the temperature of the front faceat 2,000° F. is monitored by a thermocouple. Under such conditionssamples with substantially reduced burn-off areas on the back face ofthe composite or laminate after exposure to the 2,000° F. flame for 15minutes show stabilization and thermal stability of the resin char andreduced thermal conductivity of the char, due to the presence of thepolymeric phosphorylated amide additive.

The following are examples of practice of the invention:

EXAMPLE III

30 grams of the product prepared in Example I, viz, the polymer obtainedfrom the reaction of phenylphosphonic dichloride with para-phenylenediamine, was dissolved in 135 grams of Skybond 703 polyimide varnish (acondensation type polyimide marketed by Monsanto as a 67 percent solidssolution). The resulting solution was used to impregnate 8 plies of a9-inch square 181 Fiberglass cloth (marketed by Owens Corning).

The resulting resin impregnated glass cloth laminate was vacuum baggedand maintained at 28 inches of mercury vacuum, and initially heated forone hour at 175° F. The temperature was then increased over a period of3 hours to 350° F. and maintained at that temperature for about 21/2hours. The laminate was then removed from the vacuum bag and post-curedat a temperature of 550° F. for 4 hours.

Skybond 703 is usually sold as a polyamic acid varnish which isconverted to a polyimide during heating and curing. However, Skybond 703is usually referred to as the "polyimide varnish," even though itrequires curing to convert it to the polyimide.

Samples of the resulting cured polyimide glass fabric laminate, andsamples of a polyimide-impregnated glass laminate control employing thesame amount of polyimide and using the same number of plies of 181Fiberglass cloth, as for producing the polyimide glass fabric laminateabove containing the additive of the invention, and cured by theprocedure described above, were subjected to a Meeker burner flamemaintained at 2,000° F. by means of a thermocouple, for a period of 15minutes.

For the polyimide-glass fabric laminate control a large burn-off areawas observed on the back, or rear face, of the laminate resulting fromalmost complete volatilization of resin and showed considerabledelamination. Additionally, the backside temperature was around 1,200°F. On the other hand, for the polyimide impregnated glass fabriclaminate containing the phenylphosphonic para-phenylene diamine polymerof the present example, essentially no burn-off areas on the back faceof such polyimide glass laminate were observed, and the backsidetemperature was around 500° F.

This example accordingly shows that the resin char formed at the 2,000°F. flame temperature with the polyimide glass laminate of the inventioncontaining the polymeric phosphorylated amide additive can bestabilized, and the resin char has reduced thermal conductivity. Thus,it can be seen that the presence of the polymeric phosphorylated amideadditive in the resin stabilizes the char formed, and reduces the resinburn-off on the back face of the laminate as well as reducing thethermal conductivity of the char.

EXAMPLE IV

The procedure of Example III was repeated except that 30 grams of polyphenylphosphonic polyamide was used in place of the polymer obtainedfrom the reaction of phenylphosphonic dichloride with para-phenylenediamine. The polyphenylphosphonic polyamide is obtained from a reactionof phenyl phosphonic dichloride with ammonia followed by heating thisproduct to split out ammonia to form the polyphenylphosphonic polyamidehaving the recurring structural unit ##STR28## There is essentially norein burn-off on the rear side of polyimide-glass cloth laminate treatedwith this compound, as opposed to the untreated polyimide control ofExample III, and the backside temperature was around 450° F.

EXAMPLE V

The procedure of Example IV was repeated using 30 grams of the polymericphosphorylated amide of Example IV in 100 grams of Epon 828 Epoxy resin.

EXAMPLE VI

The procedure of Example III was followed, except that 30 grams of apolymeric 1:1 reaction product of meta phenylenediamine and phenylphosphonic dichloride was used in place of the 1:1 reaction product ofphenylphosphonic dichloride and para-phenylene diamine of Example I. Aproduct was obtained that showed no resin burn-off in the rear, and thebackside temperature was around 600° F.

EXAMPLE VII

The procedure of Example III was repeated using 30 grams of the samepolymer in 100 grams of Epon 828 epoxy resin. The results were similarto Example VI.

EXAMPLE VIII

30 grams of the polymer obtained from a 1:1 reaction between paraphenylenediamine and phenyl thiophosphonic dichloride was added to 135grams of the polyimide (Skybond 703), followed by impregnating thecomposition into 8 plies of a 9-inch square of 181 Fiberglass cloth(marketed by Owens Corning), and curing the laminate as in Example III.The resulting cured laminate was subjected to a 2,000° F. Meeker burnerflame for 15 minutes. There was essentially no resin burn-off, and thebackside temperature was around 500° F.

EXAMPLE IX

The procedure of Example III was repeated using 30 grams of the polymerprepared by reacting one mole of urea with one mole ofdimethylphosphite, in place of the polymeric phosphorylated amide ofExample III. There was essentially no resin burn-off, and the backsidetemperature was around 490° F.

EXAMPLE X

The procedure of Example IX was repeated except that 30 grams of theurea/dimethylphosphite polymer was used with 90 grams of Epon 828 epoxy.The results obtained were similar to Example IX.

EXAMPLE XI

The procedure of Example IX was repeated, but using 15 grams of thepolymer prepared by reacting one mole of urea with one mole of dimethylmethylphosphonate, in place of the urea/dimethylphosphite polymer ofExample IX. The results obtained were essentially the same as those ofExample IX.

EXAMPLE XII

The procedure of Example IX was repeated, but using 40 grams of thepolymer prepared by reacting one mole of urea with one mole of diethyltrichlorophosphonate, in place of the urea/dimethylphosphite polymer ofExample IX. The results obtained were similar to those obtained inExample IX.

EXAMPLE XIII

The procedure of Example IX was repeated, but using 10 grams of thepolymer prepared in Example IIa in place of the urea/dimethylphosphitepolymer of Example IX. The results obtained were similar to thoseobtained in Example IX.

EXAMPLE XIV

The procedure of Example XIII was repeated, but using 40 grams of aproduct obtained from the reaction of two moles of hydrazine hydratewith one mole of dimethylphosphite, in place of thehydrazine/dimethylphosphite polymer of Example IIa. It should be notedthat heating the reaction product of two moles of hydrazine hydrate withone mole of dimethylphosphite results in the elimination of hydrazineand/or ammonia to form a polymeric derivative. The results obtained weresimilar to those obtained in Example XIII.

EXAMPLE XV

The procedure of Example XIII was repeated except that 40 grams of thehydrazine/dimethylphosphite polymer was used with 135 grams of aphenolic polymer of 100 percent solids (Plyophen 23-169, a product ofReichold Chemical Co.) The results obtained were similar to ExampleXIII.

EXAMPLE XVI

The procedure of Example XIII was repeated except that 32 grams of thehydrazine/dimethylphosphite polymer was used with 90 grams of Epon 828epoxy. The results obtained were similar to Example XIII.

EXAMPLE XVII

The procedure of Example XIII was repeated except that 40 grams of acopolymer prepared from the reaction of one mole of hydrazine hydratewith 0.5 mole of dimethylphosphite and 0.5 mole of dimethylmethylphosphonate was used in place of the hydrazine/dimethylphosphite polymerof Example XIII. The results obtained were similar to Example XIII.

EXAMPLE XVIII

The procedure of Example XIII was repeated except that 40 grams of apolymer prepared by reacting one mole of guanidine with one mole ofdimethylmethylphosphonate was used in place of thehydrazine/dimethylphosphite polymer of Example XIII. The resultsobtained were similar to those obtained in Example XIII.

EXAMPLE XIX

The procedure of Example XIII was repeated except that 40 grams of apolymer prepared by reacting one mole of ethylenediamine with one moleof diethylaminophosphonic dichloride was used in place of thehydrazine/dimethylphosphite polymer of Example XIII. The resultsobtained were similar to those obtained in Example XIII.

From the foregoing, it is seen that the invention provides a firebarrier composition and composite having high fire resistance and lowthermal conductivity, by incorporating therein additives in the form ofcertain polymeric phosphorylated amides, and which function to stabilizethe char formed from the resin at high temperatures, e.g. a 2,000° F.flame temperature, thereby permitting the char to hold the glass orgraphite fibers of a fibrous substrate, such as fiberglass cloth,together and maintain the structural stability and integrity of thecomposite or laminate.

Since various modifications and changes will occur to those skilled inthe art within the spirit of the invention, the invention is not betaken as limited except by the scope of the appended claims.

What is claimed is:
 1. A fire resistant composition having low thermal conductivity, comprising a mixture of an epoxy resin and a polymeric phosphorylated amide as an additive, said additive being solublized in said resin and ultimately providing a homogeneous composition capable of being permanently bonded to a structural substrate to improve char characteristics and provide low thermal conductivity thereto and to permit such substrate to maintain structural integrity thereof when employed in an amount sufficient to form a stable resin char upon being heated to an elevated temperature of about 2,000 degrees F., said polymeric phosphorylated amide being selected from the group consisting of homopolymers and copolymers having the following general formulas, respectively: ##STR29## where Y is O or S; and R is selected from the group consisting of H, alkyl containing from about 1 to about 6 carbon atoms, cycloalkyl containing from about 5 to about 7 carbon atoms, aryl containing from about 6 to about 14 carbon atoms, the corresponding halogenated alkyl and aryl groups, nitroaryl containing about 6 to about 14 carbon atoms, heterocyclic containing 5 to 6 members in the heterocyclic nucleus and O,N or S as hetero atoms, amino, alkylamino containing from about 1 to about 8 carbon atoms in the alkyl group, arylamino containing from about 6 to about 14 carbon atoms, oxyalkyl containing from about 1 to about 4 carbon atoms, and oxyaryl containing about 6 to about 14 carbon atoms; X is selected from the group consisting of --HN-- and ##STR30## where R₁ is selected from the group consisting of H, alkyl with straight chain or branched chain and having from about 1 to about 6 carbon atoms, cycloalkyl having from about 5 to about 7 carbon atoms, and aryl having from about 6 to about 14 carbon atoms, acyl containing about 1 to about 7 carbon atoms, and aroyl containing about 7 to about 11 carbon atoms; R₂ is selected from the group consisting of divalent carbonyl and divalent thiocarbonyl, ═C═NH, and ##STR31## c is from 0 to 2; n is 2 to about 1,000; A is --NR₁ R₃, where R₃ has the same values as R₁, and R₁ and R₃ can be the same or different; R₄ has the same values as R, and R and R4 can be the same or different, X' and X" have the same values as X, and X' and X" can be the same or different, and where the relationship between R and R₄, and X' and X" is such that when R and R₄ are different, X' and X" are the same, and when R and R₄ are the same, X' and X" are different; and s and t are from about 1 to 10, and s and t can be the same or different.
 2. The fire resistant composition as defined in claim 1, wherein R is hydrogen, alkyl, aryl or the chlorinated deterivatives thereof.
 3. The fire resistant composition as defined in claim 1, wherein said additive is the homopolymer of formula (a).
 4. The fire resistant composition as defined in claim 1, wherein said additive is the copolymer of formula (b).
 5. The fire resistant composition as defined in claim 1, wherein said additive is a poly(phosphinohydrazide) having the recurring structural unit: ##STR32##
 6. The fire resistant composition as defined in claim 1, where said additive is a poly(phosphinoguanide) having the recurring structural unit: ##STR33##
 7. The fire resistant composition as defined in claim 5, where R is hydrogen or alkyl.
 8. The fire resistant composition as defined in claim 6, where R is hydrogen or alkyl.
 9. The fire resistant composition as defined in claim 5, where Y is O or S and R is hydrogen or methyl.
 10. The fire resistant composition as defined in claim 6, where Y is O or S and R is hydrogen or methyl.
 11. The fire resistant composition as defined in claim 1 said additive is the copolymer having the recurring structural unit; ##STR34##
 12. The fire resistant composition as defined in claim 1 said additive is the copolymer having the recurring structural unit; ##STR35##
 13. The fire resistant composition as defined in claim 1 wherein said additive is the copolymer having the recurring structural unit; ##STR36##
 14. The fire resistant composition as defined in claim 1 wherein said additive is the copolymer having the recurring structural unit; ##STR37##
 15. The fire resistant composition as defined in claim 1, employing about 5 to about 40 parts of said additive, per 100 parts of said resin, by weight.
 16. The fire resistant composition as defined in claim 1, where n is about 2 to about
 100. 17. The fire resistant composition as defined in claim 1 wherein said additive is the homopolymer having the recurring structural unit: ##STR38##
 18. A fire resistant composition having low thermal conductivity, comprising a mixture of a polyimide resin, and a polymeric phosphorylated amide as an additive, said additive being solublized in said resin and ultimately providing a homogeneous composition capable of being permanently bonded to a structural substrate to improve char characteristics and provide low thermal conductivity thereto and to permit such substrate to maintain structural integrity thereof when employed in an amount sufficient to form a stable resin char upon being heated to an elevated temperature of about 2,000 degrees F., said polymeric phosphorylated amide being selected from the group consisting of homopolymers and copolymers having the following general formulas, respectively: ##STR39## where Y is O or S; and R is selected from the group consisting of H, alkyl containing from about 1 to about 6 carbon atoms, cycloalkyl containing from about 5 to about 7 carbon atoms, aryl containing from about 6 to about 14 carbon atoms, the corresponding halogenated alkyl and aryl groups, nitroaryl containing about 6 to about 14 carbon atoms, heterocyclic containing 5 to 6 members in the heterocyclic nucleus, and O,N or S as hetero atoms, amino, alkylamino containing from about 1 to about 8 carbon atoms in the alkyl group, arylamino containing from about 6 to about 14 carbon atoms, oxyalkyl containing from about 1 to about 4 carbon atoms, and oxyaryl containing about 6 to about 14 carbon atoms; X is selected from the groups consisting of --HN-- and ##STR40## where R₁ selected from the group consisting of H, alkyl with straight chain or branched chain and having from about 1 to about 6 carbon atoms, cycloalkyl having from about 5 to about 7 carbon atoms, and aryl having from about 6 to about 14 carbon atoms, acyl containing about 1 to about 7 carbon atoms, and aroyl containing about 7 to about 11 carbon atoms; R₂ selected from the group consisting of divalent carbonyl and divalent thiocarbonyl, ═C═NH, and ##STR41## c is from 0 to 2; n is 2 to about 1,000; A is --NH₁ R₃, where R₃ has the same values as R₁, and R₁ and R₃ can be the same or different; R₄ has the same values as R, and R and R4 can be the same or different, X' and X" have the same values as X, and X' and X" can be the same or different, and where the relationship between R and R₄, and X' and X" is such that when R and R₄ are different, X' and X" are the same, and when R and R₄ are the same, X' and X" are different; and s and t are from about 1 to 10, and s and t can be the same or different.
 19. The fire resistant composition as defined in claim 18, wherein R is hydrogen, alkyl, aryl or the chlorinated derivatives thereof.
 20. The fire resistant composition as defined in claim 18, wherein said additive is the homopolymer of formula (a).
 21. The fire resistant composition as defined in claim 18, wherein said additive is the copolymer of formula (b).
 22. The fire resistant composition defined in claim 18, wherein said additive is a poly(phosphinohydrazide) having the recurring structural unit: ##STR42##
 23. The fire resistant composition defined in claim 18, wherein said additive is a poly(phosphinoguanide) having the recurring structural unit: ##STR43##
 24. The fire resistant composition as defined in claim 22, where R is hydrogen or alkyl.
 25. The fire resistant composition as defined in claim 23, where R is a hydrogen or alkyl.
 26. The fire resistant composition as defined in claim 22, where Y is O or S and R is hydrogen or methyl.
 27. The fire resistant composition as defined in claim 23, where Y is O or S and R is hydrogen or methyl.
 28. The fire resistant composition as defined in claim 18, said additive is the copolymer having the recurring structural unit; ##STR44##
 29. The fire resistant composition as defined in claim 18, said additive is the copolymer having the recurring structural unit; ##STR45##
 30. The fire resistant composition as defined in claim 18, wherein said additive is the copolymer having the recurring structural unit: ##STR46##
 31. The fire resistant composition as defined in claim 30, where R is methyl.
 32. The fire resistant composition as defined in claim 18, wherein said additive is the copolymer having the recurring structural unit: ##STR47##
 33. The fire resistant composition as defined in claim 32, where R is methyl.
 34. The fire resistant composition as defined in claim 18, employing about 5 to about 40 parts of said additive, per 100 parts of said resin, by weight.
 35. The fire resistant composition as defined in claim 18, where n is about 2 to about
 100. 36. The fire resistant composition as defined in claim 18 wherein said additive is the homopolymer having the recurring structural unit: ##STR48##
 37. A fire resistant composition having low thermal conductivity, comprising a cured mixture of a resin and a polymeric phosphorylated amide as an additive produced by reaction of said resin and said amide at elevated temperature; and which resin is selected so that it has the following properties and characteristics: (1) the additive is soluble in the resin prior to curing and (2) when reacted with the additive such resin will form a stable resin char when heated to an elevated temperature of about 2000° F. and (3) the fire resistance of the resin is increased and its thermal conductivity is decreased when reacted with the additive and so heated; said resin and additive being capable of forming a homogenous composition and of being permanently bonded to a structural substrate to improve char characteristics and provide low thermal conductivity thereto and to permit such substrate to maintain structural integrity thereof when employed in an amount sufficient to form said stable resin char and when heated to an elevated temperature of about 2,000 degrees F.; said polymeric phosphorylated amide being selected from the group consisting of homopolymers and copolymers having the following general formulas, respectively: ##STR49## where Y is O or S; and R is selected from the group consisting of H, alkyl containing from about 1 to about 6 carbon atoms, cycloalkyl containing from about 5 to about 7 carbon atoms, aryl containing from about 6 to about 14 carbon atoms, the corresponding halogenated alkyl and aryl groups, nitroaryl containing about 6 to about 14 carbon atoms, heterocyclic containing 5 to 6 members in the heterocyclic nucleus, and O,N or S as hetero atoms, amino, alkylamino containing from about 1 to about 8 carbon atoms in the alkyl group, arylamino containing from about 6 to about 14 carbon atoms, oxyalkyl containing from about 1 to about 4 carbon atoms, and oxyaryl containing about 6 to about 14 carbon atoms; X is selected from the group consisting of --HN-- and ##STR50## where R₁ is selected from the group consisting of H, alkyl with straight chain or branched chain and having from about 1 to about 6 carbon atoms, cycloalkyl having from about 5 to about 7 carbon atoms, and aryl having from about 6 to about 14 carbon atoms, acyl containing about 1 to about 7 carbon atoms, and aroyl containing about 7 to about 11 carbon atoms; R₂ is selected from the group consisting of divalent carbonyl and divalent thiocarbonyl, ═C═NH, and ##STR51## c is from 0 to 2; n is 2 to about 1,000; A is --NR₁ R₃, where R₃ has the same values as R₁, and R₁ and R₃ can be the same or different; R₄ has the same values as R, and R and R₄ can be the same or different, X' and X" have the same values as X, and X' and X" can be the same or different, and where the relationship between R and R₄, and X' and X" is such that when R and R₄ are different, X' and X" are the same, and when R and R₄ are the same, X' and X" are different; and s and t are from about 1 to 10, and s and t can be the same or different.
 38. The fire resistant composition as defined in claim 37, wherein R is hydrogen, alkyl, aryl or the chlorinated derivatives thereof.
 39. The fire resistant composition as defined in claim 37, wherein said additive is the homopolymer of formula (a).
 40. The fire resistant composition as defined in claim 37, wherein said additive is the copolymer of formula (b).
 41. The fire resistant composition as defined in claim 37, wherein said additive is a poly (phosphinohydrazide) having the recurring structural unit: ##STR52##
 42. The fire resistant composition as defined in claim 37, wherein said additive is a poly (phosphinoguanide) having the recurring structural unit: ##STR53##
 43. The fire resistant composition as defined in claim 41, where R is hydrogen or alkyl.
 44. The fire resistant composition as defined in claim 42, where R is hydrogen or alkyl.
 45. The fire resistant composition as defined in claim 41, where Y is O or S and R is hydrogen or methyl.
 46. The fire resistant composition as defined in claim 42, where Y is O or S and R is hydrogen or methyl.
 47. The fire resistant composition as defined in claim 37, said additive is the copolymer having the recurring structural unit: ##STR54##
 48. The fire resistant composition as defined in claim 37, said additive is the copolymer having the recurring structural unit: ##STR55##
 49. The fire resistant composition as defined in claim 37, wherein said additive is the copolymer having the recurring structural unit: ##STR56##
 50. The fire resistant composition as defined in claim 37, wherein said additive is the copolymer having the recurring structural unit: ##STR57##
 51. The fire resistant composition as defined in claim 37, employing about 5 to about 40 parts of said additive, per 100 parts of said resin, by weight.
 52. The fire resistant composition as defined in claim 37, where n is about 1 to about
 100. 53. The fire resistant composition as defined in claim 49, where R is methyl.
 54. The fire resistant composition as defined in claim 50, where R is methyl.
 55. The fire resistant composition as defined in claim 37 wherein said additive is the homopolymer having the recurring structural unit: ##STR58##
 56. The fire resistant composition as defined in claim 37, said resin being a polyimide resin.
 57. The fire resistant composition as defined in claim 37, said resin being an epoxy resin.
 58. The fire resistant composition as defined in claim 37, said resin being a phenolic resin.
 59. The fire resistant composition as defined in claim 37, said resin being a silicone resin.
 60. The fire resistant composition as defined in claim 37, said resin being a polybenzimidazole resin.
 61. A fire resistant composition having low thermal conductivity, comprising a mixture of a phenolic resin, and a polymeric phosphorylated amide as an additive, said additive being solublized in said resin and ultimately providing a homogeneous composition capable of being permanently bonded to a structural substrate to improve char characteristics and provide low thermal conductivity thereto and to permit such substrate to maintain structural integrity thereof when employed in an amount sufficient to form a stable resin char upon being heated to an elevated temperature of about 2,000° F., said polymeric phosphorylated amide being selected from the group consisting of homopolymers and copolymers having the following general formulas, respectively: ##STR59## where Y is O or S; and R is selected from the group consisting of H, alkyl containing from about 1 to about 6 carbon atoms, cycloalkyl containing from about 5 to about 7 carbon atoms, aryl containing from about 6 to about 14 carbon atoms, the corresponding halogenated alkyl and aryl groups, nitroaryl containing about 6 to about 14 carbon atoms, heterocyclic containing 5 to 6 members in the heterocyclic nucleus, and O,N or S as hetero atoms, amino, alkylamino containing from about 1 to about 8 carbon atoms in the alkyl group, arylamino containing from about 6 to about 14 carbon atoms, oxyalkyl containing from about 1 to about 4 carbon atoms, and oxyaryl containing about 6 to about 14 carbon atoms; X is selected from the groups consisting of --HN-- and ##STR60## where R₁ selected from the group consisting of H, alkyl with straight chain or branched chain and having from about 1 to about 6 carbon atoms, cycloalkyl having from about 5 to about 7 carbon atoms, and aryl having from about 6 to about 14 carbon atoms, acyl containing about 1 to about 7 carbon atoms, and aroyl containing about 7 to about 11 carbon atoms; R₂ selected from the group consisting of divalent carbonyl and divalent thiocarbonyl, ═C═NH, and ##STR61## c is from 0 to 2; n is 2 to about 1,000; A is --NR₁ R₃, where R₃ has the same values as R₁, and R₁ and R₃ can be the same or different; R₄ has the same values as R, and R and R₄ can be the same or different, X' and X" have the same values as X, and X' and X" can be the same or different, and where the relationship between R and R₄, and X' and X" is such that when R and R₄ are different, X' and X" are the same, and when R and R₄ are the same, X' and X" are different; and s and t are from about 1 to 10, and s and t can be the same or different.
 62. A fire resistant composition having low thermal conductivity, comprising a mixture of a silicone resin, and a polymeric phosphorylated amide as an additive, said additive being solublized in said resin and ultimately providing a homogeneous composition capable of being permanently bonded to a structural substrate to improve char characteristics and provide low thermal conductivity thereto and to permit such substrate to maintain structural integrity thereof when employed in an amount sufficient to form a stable resin char upon being heated to an elevated temperature of about 2,000 degrees F., said polymeric phosphorylated amide being selected from the group consisting of homopolymers and copolymers having the following general formulas, respectively: ##STR62## where Y is O or S; and R is selected from the group consisting of H, alkyl containing from about 1 to about 6 carbon atoms, cycloalkyl containing from about 5 to about 7 carbon atoms, aryl containing from about 6 to about 14 carbon atoms, the corresponding halogenated alkyl and aryl groups, nitroaryl containing about 6 to about 14 carbon atoms, heterocyclic containing 5 to 6 members in the heterocyclic nucleus, and O,N or S as hetero atoms, amino, alkylamino containing from about 1 to about 8 carbon atoms in the alkyl group, arylamino containing from about 6 to about 14 carbon atoms, oxyalkyl containing from about 1 to about 4 carbon atoms, and oxyaryl containing about 6 to about 14 carbon atoms; X is selected from the groups consisting of --HN-- and ##STR63## where R₁ selected from the group consisting of H, alkyl with straight chain or branched chain and having from about 1 to about 6 carbon atoms, cycloalkyl having from about 5 to about 7 carbon atoms, and aryl having from about 6 to about 14 carbon atoms, acyl containing about 1 to about 7 carbon atoms, and aroyl containing about 7 to about 11 carbon atoms; R₂ selected from the group consisting of divalent carbonyl and divalent thiocarbonyl, ═C═NH, and ##STR64## c is from 0 to 2; n is 2 to about 1,000; A is --NR₁ R₃, where R₃ has the same values as R₁, and R₁ and R₃ can be the same or different; R₄ has the same values as R, and R and R₄ can be the same or different, X' and X" have the same values as X, and X' and X" can be the same or different, and where the relationship between R and R₄, and X' and X" is such that when R and R₄ are different, X' and X" are the same, and when R and R₄ are the same, X' and X" are different; and s and t are from about 1 to 10, and s and t can be the same or different.
 63. A fire resistant composition having low thermal conductivity, comprising a mixture of a polybenzimidazole resin, and a polymeric phosphorylated amide as an additive, said additive being solublized in said resin and ultimately providing a homogeneous composition capable of being permanently bonded to a structural substrate to improve char characteristics and provide low thermal conductivity thereto and to permit such substrate to maintain structural integrity thereof when employed in an amount sufficient to form a stable resin char upon being heated to an elevated temperature of about 2,000 degrees F., said polymeric phosphorylated amide being selected from the group consisting of homopolymers and copolymers having the following general formulas, respectively: ##STR65## where Y is O or S; and R is selected from the group consisting of H, alkyl containing from about 1 to about 6 carbon atoms, cycloalkyl containing from about 5 to about 7 carbon atoms, aryl containing from about 6 to about 14 carbon atoms, the corresponding halogenated alkyl and aryl groups, nitroaryl containing about 6 to about 14 carbon atoms, heterocyclic containing 5 to 6 members in the heterocyclic nucleus, and O,N or S as hetero atoms, amino, alkylamino containing from about 1 to about 8 carbon atoms in the alkyl group, arylamino containing from about 6 to about 14 carbon atoms, oxyalkyl containing from about 1 to about 4 carbon atoms, and oxyaryl containing about 6 to about 14 carbon atoms; X is selected from the groups consisting of --HN-- and ##STR66## where R₁ selected from the group consisting of H, alkyl with straight chain or branched chain and having from about 1 to about 6 carbon atoms, cycloalkyl having from about 5 to about 7 carbon atoms, and aryl having from about 6 to about 14 carbon atoms, acyl containing about 1 to about 7 carbon atoms, and aroyl containing about 7 to about 11 carbon atoms; R₂ selected from the group consisting of divalent carbonyl and divalent thiocarbonyl, ═C═NH, and ##STR67## c is from 0 to 2; n is 2 to about 1,000; A is --NR₁ R₃, where R₃ has the same values as R₁, and R₁ and R₃ can be the same or different; R₄ has the same values as R, and R and R₄ can be the same or different, X' and X" have the same values as X, and X' and X" can be the same or different, and where the relationship between R and R₄, and X' and X" is such that when R and R₄ are different, X' and X" are the same, and when R and R₄ are the same, X' and X" are different; and s and t are from about 1 to 10, and s and t can be the same or different. 